It is desirable to trap evaporated fuel and oil vapors within the air intake system, thereby preventing their release into the outside environment. Fuel vapors contain hydrocarbons which are known to be a significant contributing component in urban smog.
Gasoline, for example, is a highly volatile hydrocarbon fuel that includes components which transition easily from a liquid to vapor phase. Elevated temperatures such as occurring during normal internal combustion engine operation accelerate the liquid to vapor transition. The hydrocarbon vapors, unless treated or captured, may ultimately discharge into the atmosphere. It is known that hydrocarbon vapors are discharged from the engine crankcase during engine operation. When the engine is shutdown, these vapors may continue to be released from the hot engine crankcase and other components, particularly as the engine cools.
The control of hydrocarbon vapors escaping into the environment is regulated by state and federal regulations. Hydrocarbon traps for capturing hydrocarbon vapors are well known. For example, motor vehicles are commonly equipped with hydrocarbon adsorptive emissions canisters connected to the fuel tank for trapping hydrocarbon vapors, particularly as emitted during refueling.
It is known that certain porous materials such as activated carbon are useful for absorption and removal of organic hydrocarbon vapors. It is known hydrocarbon vapors are liquefied within small micro pores of the activated carbon and may be retained by absorption.
Various types of hydrocarbon traps for capturing hydrocarbon vapors are known in the art. For example, U.S. Pat. No. 5,914,294 discloses a monolithic trap which adsorbs chemical constituents from a gas stream. This is achieved by bringing the gas into direct contact with the activated carbon in the monolith. One disadvantage of this type of extruded or press formed hydrocarbon trap is that the extrusion and binding process results in a relatively brittle trap that may crack or have individual pieces flake off.
Another example is U.S. Published Application 2005/0223894 which discloses an adsorption element for adsorbing gases and vapors from the intake tract of an engine. The adsorption element has free-flow channels in an element having a spacer layer and an adsorption layer. One disadvantage of this type of corrugated trap is that the trap itself introduces a restriction to airflow in the intake tract.
Another example is in U.S. Pat. No. 8,262,785 which discloses a flat hydrocarbon adsorption traps having a first media retention layer and a second media retention layer in a spaced parallel relationship. The layers are separate sheets between which the hydrocarbon vapor adsorbent media is arranged. One disadvantage of this type of trap in the high cost of production due to the necessity of cutting the first and second media retention sheets to size, applying the hydrocarbon vapor adsorbent media on the first sheet and stacking the second sheet over the first sheet. A mounting member is then secured to the edges of the spaced sheets, the mounting member closing over the sealing the hydrocarbon vapor adsorbent media within the trap. The manufacturing process is relative complex resulting in higher cost. As the manufacturing requires several discrete components assembled in discrete steps, where the size and shape of the components is dependent upon the specific part being produced, the process is suitable of high speed low cost production.
Therefore, there remains a need in the art for a hydrocarbon adsorption trap that is producible from a single roll stock sheet media in a continuous forming process, where the process is adaptable for configurable to manufacture a variety of hydrocarbon adsorption trap for different applications from a single flexible process.